The quality of foods, drinks, drugs and the like is deteriorated by oxygen, and therefore they are desired to be stored in the absence of oxygen or under the condition with an extremely small amount of oxygen.
Accordingly, for containers or packs for storing foods, drinks, drugs and the like, glass bottles and metal cans have been used. These containers do not let oxygen permeate therethrough, but are problematic in their distribution since they are readily broken or deformed and they are heavy. Accordingly, recently, various plastic containers that are lightweight and are relatively excellent in the impact resistance have become much used. However, plastic containers have a serious problem in that, since oxygen may readily permeate through the container wall, the contents therein are deteriorated by oxygen.
Against the problem, recently, resinous containers or packing materials are made to have oxygen absorbability by themselves, while, on the other hand, gas-barrier resins are tentatively used for those that constitute containers or packing materials.
For example, Patent Reference 1 discloses a film that comprises a matrix of a thermoplastic resin such as polyester resin and, dispersed as layers in the matrix, an aromatic polyamide resin.
Patent Reference 2 discloses a packing container having an oxygen-absorbing layer that comprises a substrate resin component such as a thermoplastic polyester resin to form a continuous layer, and an oxygen-absorbing functional component that comprises a polyamide resin, an oxidizing organic component and a transition metal catalyst to form a discontinuous layer.
These packing containers could exhibit gas-barrier properties on a certain level at high temperatures owing to the water resistance of the polyester resin therein, but since the continuous layer is composed of a polyester resin which has basically no gas-barrier properties, the gas-barrier properties of the containers could not be said sufficient.
On the other hand, an oxygen gas-barrier resin composition is known, which comprises a saponified product of an ethylene/vinyl acetate copolymer serving as a gas-barrier resin and contains an oxidation catalyst such as cobalt stearate added thereto (Patent References 3 and 4).
Polyvinyl alcohol polymers such as a saponified product of an ethylene/vinyl acetate copolymer, a polyvinyl alcohol and the like are thermoplastic, to which, therefore, various shaping methods are applicable. Accordingly, they are useful as a packing container material; however, their water vapor permeability is high and their oxygen permeability greatly varies depending on humidity. Therefore, they are problematic in that their oxygen gas-barrier properties are poor especially in high-humidity environments. Films obtained by laminating such a polyvinyl alcohol polymer and a polypropylene film or the like have a problem in that the peel strength between them is low.    Patent Reference 1: JP-A 2001-164002    Patent Reference 2: JP-A 2005-112468 (WO2005/016782)    Patent Reference 3: JP-A 4-211444 (U.S. Pat. No. 5,164,438)    Patent Reference 4: JP-A 5-170980 (EP-A 0546546)